Diagnostic accuracy of triplex ultrasound in malignant parotid tumors

ABSTRACT

The gray scale sonography [GSS] in initial studies and color Doppler sonography in more recent studies have been used for evaluation of parotid tumors. The objective of this study is to evaluate the validity of triplex sonography, i.e., GSS, color Doppler mapping [CDM] and spectral Doppler sonography [SDS] to differentiate the malignant from benign parotid tumors. Fifty parotid tumors were evaluated. On GSS the tumor margin was evaluated and divided into [well-defined] and [ill-defined.] On CDM, tumors vascularity was divided into two groups of [hypovascular] [arteries] and [hypervascular] [>/= 2 arteries]. On SDS, the peak systolic velocity [PSV] of tumor arterial blood flow was measured. The diagnostic indices [sensitivity, specificity, positive predictive value and negative predictive value] of GSS, CDM and SDS findings alone and in combination were calculated, considering the histopathology results as the gold standard. For PSV, we used the receiver operating characteristic [ROC] curve analysis and calculated the area under the ROC curve. After excisional biopsy and histopathologic examination, 18 out of 50 tumors were malignant and 32 were benign. The sensitivity and specificity of the GSS was 77.8% and 90.6%, respectively. These diagnostic indices for CDM were 83.3% and 87.5%, respectively. The mean +/- SD PSV was significantly higher in malignant tumors than in benign ones [40.1 +/- 9.9 vs 19.1 +/- 4.9 cm/s] [p<0.0001]. For PSV, the area under the ROC curve was 0.98; with a cut-off point of >/= 24 cm/s; the sensitivity was 100% and the specificity was 81.2%. With a cut-off point of >/= 29 cm/s for PSV, the sensitivity was 83.3% and the specificity was 100%. Using a cut-off value of 27.5 cm/s for PSV, the sensitivity and specificity of this modality for differentiation of malignant tumors were 88.9% and 96.9%, respectively. Combining the results of triplex sonography in a scoring system showed a little improvement in the diagnostic indices. The PSV alone and combination of the GSS, CDM and SDS findings are sensitive and specific methods in differentiation of malignant parotid tumors from benign diseases